Anthropic Unveils Claude Sonnet 5 as Default, Elevating Agentic AI at Lower Cost

Anthropic released Claude Sonnet 5 as the default Claude model for Free and Pro users, promoting it as the most agentic Sonnet yet—with improved planning, tool use, and autonomous operation and performance near Opus 4.8 but at a lower price. Intro pricing through Aug 31, 2026 is $2 per million input tokens and $10 per million output tokens (standard pricing becomes $3/$15 after). The company also notes higher rate limits, ongoing Mythos 5 and Fable 5 models, and a new Claude Science desktop app for Mac and Linux.